Ford F150 Pickup. Manual — part 1406

ELECTRIC EXHAUST GAS RECIRCULATION SYSTEM MONITOR

Electric Exhaust Gas Recirculation (EEGR) system monitor is an on-board strategy designed to test integrity
and flow characteristics of EEGR system. The monitor is activated during EEGR system operation and after
certain base engine conditions are satisfied. Input from ECT or CHT, IAT, TP, CPS, MAF, and MAP sensors is
required to activate EEGR System Monitor. Once activated, EEGR system monitor will perform each test listed
during engine modes and conditions indicated. Some EEGR system monitor tests are also performed during
KOEO and KOER self-tests.

1. The motor EGR monitor consists of an electrical and functional test that checks motor and EEGR system

for proper flow. PCM controls EEGR valve by commanding from 0-52 discreet increments or "steps" to
get valve from fully CLOSED to fully OPEN position. Motor electrical test is a continuous check of 4
electric motor coils and circuits to PCM. A malfunction is indicated if an open circuit, short to power, or
short to ground has occurred in one or more motor coils/circuits for a calibrated period of time. If a
malfunction has been detected, EEGR system will be disabled, setting KOER, and Continuous Memory
DTC P0403. Additional monitoring will be suspended for remainder of driving cycle, or until next engine
start-up.

After the vehicle has warmed up and normal EEGR rates are being commanded by PCM, EEGR flow
check is performed. Flow test is performed once per drive-cycle when a minimum amount of EEGR is
requested and remaining entry conditions required to initiate test are satisfied. If a malfunction is
detected, EEGR system as well as EEGR monitor is disabled until next engine start-up.

2. EEGR flow test is done by observing the behavior of 2 different values of MAP; analog MAP sensor

reading, and inferred MAP reading (a MAP reading calculated from MAF sensor, TP sensor, RPM, etc.).
During normal, steady-state operating conditions, EEGR is intrusively commanded ON to a specified
percentage. Then, EEGR is commanded OFF. If EEGR system is working properly, there is a significant
difference in both observed and calculated values of MAP, between EEGR ON and EEGR OFF states.

When flow test entry conditions have been satisfied, EEGR is commanded to flow at a calibrated test rate
(about 10 percent). At this time, value of MAP is recorded (EEGR ON MAP). Value of inferred MAP
EEGR ON IMAP is also recorded. Next, EEGR is commanded OFF (zero percent). Again, value of MAP
is recorded (EEGR OFF MAP). Value of EEGR OFF IMAP is also recorded. Typically, 7 such ON/OFF
samples are taken. After all samples have been taken, the average EEGR ON MAP, EEGR ON IMAP,
EEGR OFF MAP and EEGR OFF IMAP values are stored.

3. The differences between EEGR ON and EEGR OFF values are calculated.

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MAP-Delta = EEGR ON MAP - EEGR OFF MAP (Analog MAP)

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IMAP-Delta = EEGR ON IMAP - EEGR OFF IMAP (Inferred MAP)

If the sum of MAP-Delta and IMAP-Delta exceeds a maximum threshold or falls below a minimum
threshold, DTC P0400 (high or low flow malfunction) is stored.

4. As an additional check, if EEGR ON MAP exceeds a maximum threshold (BARO - a calibrated value), a

DTC P0400 (low flow malfunction) is stored. This check is performed to detect reduced EEGR flow on
systems where MAP pickup point is not located in intake manifold, but is located just upstream of EEGR
valve in EEGR delivery tube.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

5. If inferred ambient temperature is less than 20°F (-7°C), more than 130°F (54°C), or altitude is more than

8000 feet (BARO less than 22.5 in. Hg), EEGR flow test cannot be reliably done. In these conditions,
EEGR flow test is suspended and a timer starts to accumulate the time in these conditions. If vehicle
leaves these extreme conditions, timer starts and if conditions permit, will attempt to complete EEGR
flow monitor. If timer reaches 500 seconds, EEGR flow test is disabled for remainder of current driving
cycle and EEGR monitor I/M readiness bit will be set to a "ready" condition.

DTC P1408 is like DTC P0400. It will indicate an EEGR flow failure (outside minimum or maximum limits)
but is only set during KOER self-test. DTC P0400 and P0403 will illuminate MIL. DTC P1408 will not
illuminate MIL.

FUEL SYSTEM MONITOR

Fuel System Monitor is an on-board strategy designed to monitor the fuel trim system. The fuel control system
uses fuel trim tables stored in PCM Keep Alive Memory (KAM) to compensate for variability in fuel system
components due to normal wear and aging. During closed-loop vehicle operation, fuel trim strategy learns
corrections needed to correct a "biased" rich or lean fuel system. Correction is stored in fuel trim tables. Fuel
trim has 2 means of adapting; a Long Term Fuel Trim (LONGFT) and a Short Term Fuel Trim (SHRTFT).
Long term relies on fuel trim tables and short term refers to desired air/fuel ratio parameter "LAMBSE". For
additional fuel trim information, see FUEL TRIM under POWERTRAIN CONTROL MODULE SOFTWARE
under COMPUTERIZED ENGINE CONTROLS in THEORY & OPERATION - CNG, FLEX-FUEL &
GASOLINE article. Input from ECT or CHT, IAT, and MAF sensors is required to activate fuel trim system,
which in turn activates fuel system monitor. Once activated, fuel system monitor looks for fuel trim tables to
reach adaptive clip and LAMBSE to exceed a calibrated limit. Fuel system monitor will store appropriate DTC
when a fault is detected as follows.

1. Heated Oxygen Sensor (HO2S) detects presence of oxygen in exhaust and provides PCM with feedback

indicating air/fuel ratio.

2. A correction factor is added to fuel injector pulse width calculation according to long and short term fuel

trims as needed to compensate for variations in fuel system.

3. When deviation in the parameter LAMBSE increases, air/fuel control suffers and emissions increase.

When LAMBSE exceeds a calibrated limit and the fuel trim table has clipped, the Fuel System Monitor
sets a Diagnostic Trouble Code (DTC) as follows:

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DTCs P0171 and P0174 are associated with monitor detecting a lean shift in fuel system operation.

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DTCs P0172 and P0175 are associated with the monitor detecting a rich shift in fuel system
operation.

4. MIL is activated after a fault is detected on 2 consecutive drive cycles.

Typical Fuel System Monitor Entry Conditions:

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RPM range between Idle and 4000 RPM.

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Air Mass Range greater than 0.75 lb/min.

NOTE:

BARO is inferred at engine start-up using KOEO MAP sensor reading. It is
updated during high, part-throttle or high RPM engine operation.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

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Purge duty cycle of 0 percent.

Typical Fuel Monitor Malfunction Thresholds:

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Lean Malfunction: LTFT > 25 percent, STFT > 5 percent.

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Rich Malfunction: LTFT < 25 percent, STFT < 10 percent.

HEATED OXYGEN SENSOR MONITOR

Description

Heated Oxygen Sensor (HO2S) monitor is an on-board strategy designed to monitor HO2S sensors for a
malfunction or deterioration which can affect emissions. The fuel control or upstream HO2S is checked for
proper output voltage and response rate (time it takes to switch from lean to rich or rich to lean). Downstream
HO2S sensors used for catalyst monitor are also monitored for proper output voltage. Input is required from
ECT or CHT, IAT, MAF and CKP sensors to activate HO2S monitor. Fuel system monitor and misfire
detection monitor must also have completed successfully before HO2S monitor is enabled.

1. The HO2S sensor senses the oxygen content in the exhaust flow and outputs a voltage between zero and

one volt. Lean of stoichiometric (air/fuel ratio of approximately 14.7:1), the HO2S will generate a voltage
between zero and 0.45 volt. Rich of stoichiometric, the HO2S will generate a voltage between 0.45 and
one volt. The HO2S Monitor evaluates the Stream 1 (Fuel Control) and Stream 2 (Catalyst Monitor) and
the Stream 3 (FAOS Control) HO2Ss for proper function.

2. Once the HO2S Monitor is enabled, the Stream 1 HO2S signal voltage amplitude and response frequency

are checked. Excessive voltage is determined by comparing the HO2S signal voltage to a maximum
calibratable threshold voltage. A fixed frequency closed loop fuel control routine is executed and the
Stream 1 HO2S voltage amplitude and output response frequency are observed. A sample of the Stream 1
HO2S signal is evaluated to determine if the sensor is capable of switching or has a slow response rate. A
HO2S heater circuit fault is determined by turning the heater on and off and looking for a corresponding
change in the Output State Monitor (OSM) and by measuring the current going through the heater circuit.
Since the 2002 Model Year, vehicles will monitor the HO2S signal for a high voltage, in excess of 1.5
volts.

3. MIL is activated after a fault is detected on 2 consecutive drive cycles.

HO2S monitor DTCs can be categorized as follows:

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HO2S signal circuit malfunction - P0131, P0136, P0151, P0156.

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HO2S slow response rate - P0133, P0153.

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HO2S circuit high voltage - P0132, P0138, P0144, P0152, P0158, P0164.

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HO2S heater circuit malfunction - P0135, P0141, P0155, P0161, P0147, P0167.

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HO2S heater current malfunction - P0053, P0054, P0055, P0059, P0060, P0061.

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Downstream HO2S not running in on-demand self-test - P1127.

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Swapped HO2S connectors - P0040, P0041, P1128, P1129, P2278.

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HO2S lack of switching - P1131, P1132, P1151, P1152, P2195, P2196, P2197, P2198.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

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HO2S lack of switching (Sensor indicates lean) - P1137, P1157, P2270, P2272, P2274, P2276.

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HO2S lack of switching (Sensor indicates rich) - P1138, P1158, P2271, P2273, P2275, P2277.

HO2S Testing

When one of the HO2S tests is chosen and "Trigger" is pressed, NGS will display a screen that provides HO2S
test results. See Fig. 3. Test results are from the most recent OBD-II drive cycle monitoring of HO2S. Test
results will be updated each time a monitoring session occurs. The monitor within PCM compares certain PIDs
to stored parameters and provides "Pass" or "Fail" information.

Fig. 3: NGS Tester Oxygen Sensor Test Results Display
Courtesy of FORD MOTOR CO.

MISFIRE DETECTION MONITORING

Misfire Detection Monitor is an on-board strategy designed to monitor engine misfire and identify a specific
cylinder in which misfire has occurred. Misfire is defined as lack of combustion in a cylinder due to absence of
spark, poor fuel metering, poor compression, or any other cause. Misfire Detection Monitor will be enabled
only when certain base engine conditions are first satisfied. Input from ECT or CHT, MAF and CKP sensors is
required to enable the monitor. Misfire Detection Monitor is also performed during KOEO and KOER self-test.
The following occurs during Misfire Detection Monitor:

1. PCM synchronized ignition spark is based on information received from CKP sensor. CKP signal

generated is also main input used in determining cylinder misfire.

2. Input signal generated by CKP sensor is derived by sensing the passing of teeth from crankshaft position

wheel mounted on end of crankshaft.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline